Correct Answer: A. Delirium
The Confusion Assessment Method (CAM) is a validated, rapid diagnostic tool specifically designed to identify delirium in clinical settings. Delirium is an acute, fluctuating state of altered consciousness with inattention, disorganized thinking, and psychomotor changes—hallmarks that CAM directly captures. The tool assesses four core features: (1) acute onset and fluctuating course, (2) inattention, (3) disorganized thinking, and (4) altered level of consciousness. A diagnosis of delirium requires features 1 and 2, plus either 3 or 4. In Indian hospital practice, CAM is widely used in ICUs, post-operative wards, and geriatric units to rapidly screen for delirium, which is common in hospitalized elderly patients and those with sepsis, metabolic derangements, or medication toxicity. CAM has high sensitivity (94–100%) and specificity (90–95%) for delirium detection, making it the gold standard bedside screening tool. Unlike other psychiatric conditions, delirium is an organic mental disorder requiring urgent identification and treatment of the underlying medical cause (infection, hypoxia, electrolyte imbalance, drug withdrawal, etc.). This acute, reversible nature and focus on consciousness/attention disturbance is what CAM specifically targets.
Why the other options are wrong
B. Depression — Depression is a mood disorder characterized by persistent low mood, anhedonia, and guilt—not acute confusion or fluctuating consciousness. CAM does not assess mood symptoms. While depression may coexist with delirium, CAM is not designed to diagnose or screen for primary depressive disorder. The absence of acute onset and inattention in depression makes CAM inappropriate. C. Schizophrenia — Schizophrenia is a primary psychotic disorder with hallucinations, delusions, and negative symptoms, but typically has insidious onset and preserved consciousness/attention. CAM specifically targets acute fluctuating confusion and inattention, which are not core features of schizophrenia. Schizophrenia requires different diagnostic criteria (DSM-5/ICD-10), not CAM. D. Dementia — Dementia is a chronic, progressive neurodegenerative condition with insidious onset over months to years, whereas CAM is designed for acute onset and fluctuating course. While delirium may be superimposed on dementia (delirium superimposed on dementia, or DSD), CAM is not the primary diagnostic tool for dementia itself. Dementia diagnosis relies on cognitive testing (MMSE, MoCA) and neuroimaging, not CAM.
High-Yield Facts
- CAM (Confusion Assessment Method) is the gold-standard rapid bedside screening tool for delirium, not other psychiatric disorders.
- Delirium diagnostic criteria require acute onset + fluctuating course + inattention + (disorganized thinking OR altered consciousness)—all captured by CAM.
- CAM sensitivity 94–100%, specificity 90–95% for delirium; widely used in Indian ICUs, post-op wards, and geriatric units.
- Delirium is an organic mental disorder requiring urgent identification and treatment of underlying medical cause (sepsis, hypoxia, drugs, metabolic derangement).
- Dementia vs. delirium: dementia is chronic/insidious; delirium is acute/fluctuating—CAM targets the latter.
- CAM-ICU is the ICU-adapted version for non-verbal or sedated patients; widely used in Indian tertiary care.
Mnemonics
CAM-4 Features for Delirium Acute onset + Fluctuating course + Inattention + (Disorganized thinking OR altered consciousness). Diagnosis = A + F + (I + D/C). Use: rapid bedside screening in hospital/ICU. Delirium vs. Dementia (ACUTE vs. CHRONIC) Delirium: ACUTE onset, fluctuating, reversible, inattention prominent. Dementia: CHRONIC onset, progressive, irreversible, memory loss prominent. CAM screens for ACUTE—delirium only.
NBE Trap
NBE may pair CAM with dementia to trap students who confuse acute delirium superimposed on chronic dementia (DSD) with primary dementia diagnosis. CAM is for acute delirium screening, not dementia diagnosis.
Clinical Pearl
In Indian hospital practice, an elderly patient post-operatively or with sepsis presenting with acute confusion and inattention is screened with CAM at bedside—a positive CAM triggers urgent investigation for infection, metabolic derangement, or medication toxicity, often leading to life-saving intervention. This rapid identification is why CAM is standard in Indian ICUs and geriatric wards.
_Reference: Harrison Ch. 41 (Delirium & Altered Mental Status); Robbins Ch. 28 (Nervous System); KD Tripathi Ch. 8 (Psychopharmacology & Organic Mental Disorders)_